35x2-21x-7=0

Solution for 35x2-21x-7=0 equation:

35x^2-21x-7=0

a = 35; b = -21; c = -7;
Δ = b2-4ac
Δ = -212-4·35·(-7)
Δ = 1421
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1421}=\sqrt{49*29}=\sqrt{49}*\sqrt{29}=7\sqrt{29}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-21)-7\sqrt{29}}{2*35}=\frac{21-7\sqrt{29}}{70}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+7\sqrt{29}}{2*35}=\frac{21+7\sqrt{29}}{70}
$